Fabrication method of flat panel display comprising address line with mending layer

ABSTRACT

A structure and a fabrication method of a flat panel display comprising address lines with mending layers. A first address line and a first mending layer are formed on a substrate. The first mending layer and the first address line are electrically insulated with each other, and the first mending layer is partitioned into different segments by the first address line. A first insulating layer is formed over the substrate to cover at least the first mending layer and the first address line. A second address line is formed on the first insulating layer over the first mending layer and crossing the first address line. A second insulating layer is formed over the substrate to cover at least the second address line. A second mending layer is formed on the second insulating layer over the second address line and crossing the first address line.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of, and claims the prioritybenefit of, U.S. application Ser. No. 09/767,340 filed on Jan. 23, 2001,now U.S. Pat. No. 6,515,301.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates in general to a structure and a fabrication methodof a flat panel display comprising address lines. More particularly,this invention relates to a structure and a fabrication method of a flatpanel display comprising address lines having mending layers.

2. Description of the Related Art

In the operation of a flat panel display, two orthogonal address lines,namely, scan lines and data lines, are used to control the pixelsarranged in a matrix for image display. The scan lines and the datalines are perpendicular to each other. Each intersection of the scanlines and the data lines is located near by a pixel. During theoperation of the flat panel display, each scan line is drivensequentially, and the status of each corresponding pixel, that is, theimage shown on the flat panel display, is changed according to thetransmission signal from each data line.

The scan lines and data lines have to be long enough to cross the wholedisplay area of the flat panel display device. Due to certain amount ofinevitable defects or contamination, defective scan lines or data linesare often found on the substrate. As a consequence, pixels connected tothose defective lines could not receive data signal sand displayproperly. Accordingly, some mending methods are proposed.

For example, when one of the data lines is broken, a metal linedeposited around the display area is welded and electrically connectedwith the two terminals of the broken data line. Accordingly, all pixelsalong the broken data line receive data signal at the same time fromboth terminals. However, this method might induce higer straycapacitance and resistance As a result, pixels connected with the brokendata line would abnormally operat. That is, the overall image quality ofthe flat panel display is degraded. In addition, if a defect happens toa scan line and mended by the above-mentioned method, high straycapacitance would also cause a serious RC delay for the scan line. TheRC delay would distort scan voltage waveform along the scan line resultin a weak line.

SUMMARY OF THE INVENTION

The present invention provides a method of fabricating an address linehaving a mending layer on a flat panel display. A substrate is provided.A first address line and a first mending layer are formed on thesubstrate. The first mending layer is electrically insulated from thefirst address line. The first mending layer is partitioned intodifferent segments by the first address line. A first insulating layeris formed over the substrate to cover at least the first address lineand the first mending layer. A second address line is formed on thefirst insulating layer over the first mending layer and crosses thefirst address line. A second insulating layer is formed over thesubstrate to cover at least the second address line. A second mendinglayer is formed on the second insulating layer over the second addressline and crosses the first address line. Preferably, a coverage of thesecond mending layer is partly overlapped with the first mending layerat two sides of the first address line. Besides, it is preferable thatthe material for forming the first address line and the first mendinglayer is the same, and the first address line and the first mendinglayer are formed simultaneously.

In the above method, a third mending layer can further be formed overthe first address line while forming the second address line. The thirdmending layer is electrically insulated from the second address line.

The present invention further provides a structure of an address linehaving a mending layer on a flat panel display. The structure comprisesa first address line, a first mending layer, a first insulating layer, asecond address line, a second insulating layer and a second mendinglayer. The first address line and the first mending layer areelectrically insulated from each other and formed on an insulatingsubstrate. The first mending layer is partitioned into differentsegments by the first address line. The first insulating layer covers atleast the first address line and the first mending layer. The secondaddress line is located on the first insulating layer over the mendinglayer and crosses the first address line. The second insulating layercovers at least the second address line. The second mending layer islocated on the second insulating layer over the second address line andcrosses the first address line.

The above structure further comprises a third mending layer located onthe first insulating layer over the first address line and electricallyinsulated from the second address line.

In addition, in the above method and structure, the first address lineincludes a scan line and the second address line includes a data line.It is preferable that the second mending layer is made of a materialsimilar to that of the pixel on the flat panel display. The secondmending layer can be formed simultaneously with the pixel to simplifythe fabrication process.

The address line having a mending layer can solve the problem of brokenline on a flat panel display. As mentioned above, the first mendinglayer is formed under the data line in a flat panel display. When adefective point happens to the data line, the first mending layerlocated below the defective point is laserwelded and connectedelectrically with the data line. The data line is thus mended with thefirst mending layer. In specific case, when the defective point islocated on the intersection portion of the data line over the scan line,the second mending layer is welded and electrically connected with twoends of the data line. Therefore, with the coverage of the secondmending layer partly overlapping the coverage of the first mending layeron both sides of the first address line, no matter where the defectivepoint is located on the data line, it can be easily repaired.

In addition, the third mending layer can be further formed over the scanline. Therefore, when a defective point happens to the scan line, thethird mending layer can be welded and electrically connected with thebroken scan line.

The first mending layer can be used to mend the broken data linethereon, the second mending layer is used to mend the broken part of thedata line located at an intersection between the data line and the scanline, and the third mending layer is used to mend the underlying brokenscan line. Therefore, without external bonding or wiring, the brokenaddress lines (the data line and the scan line) can be mended to ensurea normal operation of every single pixel. The yield is thus greatlyimproved.

Both the foregoing general description and the following detaileddescription are exemplary and explanatory only and are not restrictiveof the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 2A, 3A and 4A are top views showing a structure andfabrication process of address lines having mending layers of a thinfilm transistor (TFT) liquid crystal display;

FIGS. 1B and 2B are cross sectional views along the line I—I in FIGS. 1Aand 2A, respectively;

FIG. 2C is a cross sectional view along the line III—III in FIG. 2A,

FIG. 2D is a cross sectional view of FIG. 2A along the line IV—IV;

FIG. 3B is a cross sectional view along the line V—V in FIG. 3A;

FIG. 4B is a cross sectional view along the line VI—VI in FIG. 4A;

FIG. 4C is a cross sectional view along the line VII—VII in FIG. 4A;

FIGS. 5-7 shows the mending condition when the address lines ofthin-film transistor liquid crystal display are broken.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1A and 1B, a substrate 100, for example, aninsulating substrate, is provided. Using metal deposition andphotolithography and etching processes, a gate 110, a scan line 120connected to the gate 110 and a mending layer 130 are formed on thesubstrate 100. The mending layer 130 and the scan line 120 areelectrically insulated from each other. The mending layer 130 is furtherpartitioned into different sections by the scan line 120. The materialfor forming the gate 110, the scan line 120 and the mending layer 130are similar. Furthermore, the gate 110, the scan line 120 and themending layer 130 can be formed simultaneously to simplify thefabrication process.

Referring to FIGS. 2A to 2D, an insulating layer 135 is formed over thesubstrate 100 to cover at least the scan line 120 and the mending layer130. In this embodiment, the gate 110 is also covered with theinsulating layer 135. The portion of the insulating layer 135 coveringthe gate 110 is to be formed as the gate insulating layer in a thin filmtransistor. The material of the insulating layer 135 includes, forexample, silicon nitride.

In FIG. 2D, a channel layer 137 is formed on the portion of theinsulating layer 135 that covers the gate 110. A heavily dopedsemiconductor layer 138 is further formed on the channel layer 137. Asshown in FIGS. 2A to 2D, a data line 150 is then formed on theinsulating layer 135. A portion of the data line located on the heavilydoped semiconductor layer 138, denoted as 140, is the source/drainconducting layer 140. Meanwhile, a mending layer 160 is also formed onthe insulating layer 135 aligned over the scan line 120. The data line150 is formed aligned over the mending layer 130 and crossing the scanline 120. The mending layer 160 is electrically insulated from the dataline 150, and the mending layer 160 can be partitioned into differentsections by the data line 150, as shown in FIGS. 2A and 2C.

Referring to FIGS. 3A and 3B, a patterned passivation layer 170 isformed to cover the data line 170, the mending layer 160, thesource/drain conducting layer 140 and the peripheral regions thereof.The passivation layer 170 comprises an opening 170 to expose a part ofthe source/drain conducting layer 140 to provide an electricalconnection between the source/drain conducting layer 140 and the pixelelectrodes formed subsequently.

As shown in FIGS. 4A and 4B, a mending layer 190 is formed on thepassivation layer 170, and a pixel electrode 180 is formed toelectrically connect the source/drain conducting layer 140. The mendinglayer 190 is aligned over the data line 150 and across the scan line120. Preferably, the mending layer 190 and the pixel electrode 180 areformed of the same material, for example, indium tin oxide (ITO)simultaneously.

Referring to FIGS. 4A to 4C, after the above processes, in the thin filmtransistor liquid crystal display, the address lines include the dataline 150 and the scan line 120 and the mending layers 130, 160 and 190.In addition, the thin film transistor liquid display further includesthe substrate 100, the gate 110, the insulating layers 135, the channellayer 137, the heavily doped semiconductor layer 138, the source/drainconducting layer 140, the passivation layer 170 and the pixel electrode180.

The above scan line 120, gate 110 and mending layer 130 are formed onthe substrate 100. The mending layer 130 and the scan line 120 areelectrically insulated from each other. The mending layer 130 is furtherpartitioned into different sections by the scan line 120. The insulatinglayer 130 is located on the scan line 120, the mending layer 130 and thegate 110. The channel layer 137 is located on the insulating layer 135aligned over the gate 110. The heavily doped semiconductor layer 138 islocated on the channel layer 137. The data line 150 is located on theinsulating layer 130 aligned over the mending layer 130 crossing thescan line 120. The source/drain conducting layer 140 is formed on theheavily doped semiconductor layer 138. The mending layer 160 is locatedon the insulating layer 135 aligned over the scan line 120 and iselectrically insulated from the data line 150. The passivation layer 170is located on the source/drain conducting layer 140, the data line 150and the mending layer 160. The pixel electrode 180 penetrates throughthe passivation layer 170 to electrically connect the source/drainconducting layer 140. The mending layer 190 is located on thepassivation layer 170 aligned over the data line 150 crossing the scanline 120.

In the above structure, the mending layer 160 can be made of a materialfor forming the data line 150 and the source/drain conducting layer 140.The material for forming the mending layer 130 is the same as those forforming the scan line and the gate 110. The materials for forming themending layer 190 and the pixel electrodes are, for example, indium tinoxide. In addition, preferably, the coverage of the mending layer 130and the coverage of the mending layer 130 partly overlap with each otherto ensure every portion of the data line 150 can be mended as required.

In FIG. 5, as a mending layer 130 is formed under the data line 150,when the data line 150 is broken, the broken part 190 of the data line150 can be mended by laser welding and electrically connecting the dataline 150 on both sides of the broken part 190 with the mending layer130. In other words, by melting portions of the data line 150, theinsulating layer 135 and the mending layer 130, two conductive material202 are formed between the mending layer 130 and the data line 150.Therefore, two broken parts of data line 150 are electrically connectedwith each other.

In FIG. 6, as the mending layer 190 is formed across the scan line 120,when the data line 150 across the scan line 120 is broken, the data line150 can be electrically connected again by laser welding the mendinglayer 190 and the data line 150. That is, portions of the mending layer190, the passivation layer 170 and the data line 150 are melted toelectrically connect the broken parts of the data lines 150 via twoconducting blocks 204 between the mending layer 190 and the data line150 in the passivation layer 170. Therefore, as the coverage of themending layer 190 and the coverage of the scan line 120 partly overlapwith each other, it is ensured that no matter where the broken partoccurs, the data line 150 can be mended.

In FIG. 7, the mending layer 160 is formed over the scan line 120. Whenthe scan line 120 is broken, the scan line 120 at the two sides of thebroken part 196 can be electrically connected again by laser welding thescan line 120, the insulating layer 135 and the mending layer 160 intotwo conductive blocks 206. Each side of the scan line 120 is thusconnected with the mending layer 160 via each of the conductive blocks206.

As mentioned above, the mending layer 130 under the data line 150 can beused to mend the broken data line 150. The mending layer 190 over thedata line 150 can be used to mend the data line 150 over the scan line120, and the mending layer 160 can be used to mend the broken scan line120. Therefore, instead of using the conventional bonding or wiring viaexternal metal line, the broken data line and scan line can be mended tomaintain a normal operation of the pixels. The display quality of thedisplay can be improved, and the products that comprise such defects canbe mended easily.

Other embodiments of the invention will appear to those skilled in theart from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples to be considered as exemplary only, with a true scope andspirit of the invention being indicated by the following claims.

What is claimed is:
 1. A method for fabricating a flat panel displaycomprising address lines with mending layers on a substrate, the methodcomprising: forming a first address line and a first mending layer onthe substrate, wherein the first address line and the first mendinglayer are electrically insulated from each other, and the first mendinglayer is partitioned into different segments by the first address line;forming a first insulating layer over the substrate to cover at leastthe first address line and the first mending layer; forming a secondaddress line on the first insulating layer substantially over the firstmending layer and across the first address line; forming a secondinsulating layer over the substrate to cover at least the second addressline; and forming a second mending layer on the second insulating layersubstantially aver the second address line and across the first addressline.
 2. The method according to claim 1, wherein the step of formingthe second address line further comprises simultaneously forming a thirdmending layer on the first insulating layer substantially over the firstaddress line, the third mending layer being electrically insulated fromand partitioned into different segments by the second address line. 3.The method according to claim 1, wherein the step of forming the secondmending layer comprising a step of forming the second mending layer witha coverage partly overlapping a coverage of the first mending layer atthe two sides of the first address line.
 4. The method according toclaim 1, wherein the step of forming the first address line and thefirst mending layer comprises a step of forming the first address lineand the first mending layer simultaneously.
 5. The method according toclaim 1, wherein the step of forming the second mending layer furthercomprises simultaneously forming a pixel electrode with a same materialas the second mending layer.
 6. A method of fabricating a thin filmtransistor liquid crystal display comprising address lines with mendinglayers, the method comprising: forming a scan line, a gate and a firstmending layer on a substrate, wherein the first mending layer iselectrically insulated from the scan line and is partitioned intodifferent segments by the scan line; forming an insulating layer overthe substrate to cover at least the scan line, the gate and the firstmending layer; forming a channel layer on the insulating layer over thegate; forming a heavily doped semiconductor layer on the channel layer;forming a data line on the insulating layer substantially over the firstmending layer and crossing the scan line, wherein a portion of the dataline formed over the heavily doped semiconductor layer as a source/drainconducting layer; forming a passivation layer over the substrate tocover at least the data line and a portion of the source/drainconducting layer, while the other portion of the source/drain conductinglayer is exposed by an opening in the passivation layer; and forming asecond mending layer on the passivation layer substantially over thedata line and a pixel electrode to connect the exposed source/drainconducting layer, wherein the second mending layer crosses the scanline.
 7. The method according to claim 6, wherein the step of formingthe data line further comprising simultaneously forming a third mendinglayer on the insulating layer substantially over the scan line, thethird mending layer being electrically insulated from the data line andpartitioned into different segments by the data line.
 8. The methodaccording to claim 6, wherein the step of forming the second mendinglayer comprises forming the second mending layer with a coverage partlyoverlapping with a coverage of the first mending layer at the two sidesof the scan line.
 9. The method according to claim 6, wherein the stepof forming the gate, the scan line and the first mending layer comprisessimultaneously forming the gate, the scan line and the first mendinglayer with an identical material.
 10. The method according to claim 6,wherein the step of forming the second mending layer and the pixelelectrode comprises a step of simultaneously forming the second layerand the pixel electrode with an identical material.
 11. The methodaccording to claim 6, wherein the step of forming the second mendinglayer and the pixel electrode comprising forming the second mendinglayer and the pixel electrode with indium tin oxide.